Conventionally, an anti-fuse memory having a configuration disclosed in U.S. Pat. No. 6,667,902 (Patent document 1) has been known as a one-time programmable anti-fuse memory, which allows one-time programming through breaking an insulating film. The anti-fuse memory disclosed in the Patent document 1 includes a two-transistor configuration, in which a switch transistor and a memory capacitor are disposed adjacent to each other in a well.
In a switch transistor including a transistor configuration, a switch gate electrode is disposed on the well via a switch gate insulating film. A word line is connected to the switch gate electrode. A bit line is connected to one of diffusion regions disposed on the well. A memory gate electrode of the memory capacitor, which forms a pair with the switch transistor, is disposed on the well via a memory gate insulating film. A programming word line, which is different from the word line connected to the switch gate electrode, is connected to the memory gate electrode.
At the time of data programming operation, dielectric breakdown of the memory gate insulating film of the memory capacitor is caused by a voltage difference between a breakdown word voltage and a breakdown bit voltage. The breakdown word voltage is applied from the programming word line to the memory gate electrode. The breakdown bit voltage is applied to the bit line of the switch transistor. Due to the dielectric breakdown of the memory gate insulating film, the memory gate electrode, which has been insulated from the well, is electrically connected the surface of the well, that is, a region in which a memory channel is to be formed.
In a case where the memory gate insulating film has been broken at the time of data reading operation, when a voltage is applied to the programming word line connected to the bit line to be read, the voltage applied to the programming word line is applied to the other diffusion region of the switch transistor through the memory channel. The switch transistor is turned on by the voltage applied from the word line connected to the switch gate electrode and the voltage applied from the bit line connected to the diffusion region. The switch transistor determines an electrical connection state between the memory gate electrode of the corresponding memory capacitor and the memory channel through a change in the voltage applied to the bit line. Thus, the switch transistor determines whether the data has been programmed or not.